Bi-modal emulsions

ABSTRACT

A process for preparing bi-modal water emulsions is disclosed comprising: I) forming a mixture comprising; A) 100 parts by weight of a hydrophobic oil, B) 1 to 1000 part by weight of a water continuous emulsion having at least one surfactant, II) admixing additional quantities of the water continuous emulsion and/or water to the mixture from step I) to form a bi-modal emulsion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage of International PatentApplication No. PCT/US2012/027448, filed on Mar. 2, 2012, which claimspriority to and all the advantages of U.S. Application No. 61/448,849,filed on Mar. 3, 2011, the content of which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

While numerous advancements have been made in the emulsions field, thereare several long standing needs that remain. For example, as the percentsolids of an emulsion increases, in most emulsions the viscosity alsoincreases. Emulsions having a solids level greater than 75 weight % canbecome so viscous that they are non-pourable. This effectively renderssuch emulsion products unusable in many applications due to the handlingdifficulties of such viscous compositions.

Another long standing need in this field is to stabilize emulsions witha minimal amount of surfactants. This is a particular need when theemulsions are used to form coatings, such as protective architecturalcoatings. Residual surfactant on coatings formed from emulsions can haveseveral detrimental effects on the physical property profile of thecoatings such as decreased hydrophobicity and/or poorer dirt resistance.The use of emulsions with minimal amount of surfactants is also highlydesirable for application in personal care products, especially for skinand cosmetic formulations where residual surfactants may cause skinirritation.

Reducing the presence of solvents, un-reacted siloxanes, catalystresidues, cyclic polymerization byproducts, and other impurities insilicone emulsions is an ongoing challenge in the art. The need toreduce such impurities may arise, among other reasons, when suchimpurities are incompatible with downstream applications (for example,medical, cosmetic, and personal care applications), where the presenceof such impurities would reduce the stability of an emulsion, or whereregulatory requirements require removal or reduction of their presence.In particular, there is an interest to reduce the presence ofcyclosiloxanes, such as octamethylcyclotetrasiloxanes anddecamethylcyclopentasiloxanes, in silicone emulsions.

Thus, a need exists to identify a process that provides emulsionproducts having high solids contents that remain pourable. A furtherneed exists to reduce the concentration of surfactants in emulsionproducts, especially at high solid content emulsions. Yet, a furtherneed exists to provide silicone emulsions having reduced content ofcyclosiloxane concentrations.

BRIEF SUMMARY OF THE INVENTION

The present inventors have discovered a process that provides highsolids content emulsions having lower viscosities than emulsions ofsimilar solids content prepared by other methods. The present disclosurerelates to a process for preparing bi-modal water emulsions, that is,water continuous emulsions containing at least two distinct dispersedphases. The present disclosure provides a process for making a bi-modalwater continuous emulsion comprising:

I) forming a mixture comprising;

-   -   A) 100 parts by weight of a hydrophobic oil,    -   B) 1 to 1000 part by weight of a water continuous emulsion        having at least one surfactant,

II) admixing additional quantities of the water continuous emulsionand/or water to the mixture from step I) to form a bi-modal emulsion.

The inventors believe the present process is advantageous due to itsversatility to prepare a wide range of bi-modal emulsions having highsolids content. The disclosed process may be used to prepare a varietyof bi-modal emulsions having two distinct dispersed phases. Eachdistinct phase may contain either organic or silicone oil.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure provides a process for making a bi-modal watercontinuous emulsion comprising:

I) forming a mixture comprising;

-   -   A) 100 parts by weight of a hydrophobic oil,    -   B) 1 to 1000 part by weight of a water continuous emulsion        having at least one surfactant,

II) admixing additional quantities of the water continuous emulsionand/or water to the mixture from step I) to form a bi-modal emulsion.

The present process provides bi-modal emulsions. The bi-modal emulsionsare water continuous emulsions having two distinct dispersed phases. Asused herein, “dispersed phase” refers to the water insoluble particlessuspended in the continuous aqueous phase of the emulsion. The firstdispersed phase contains a hydrophobic oil while the independent seconddispersed phase also contains a hydrophobic oil, which may be the sameor different from the hydrophobic oil in the first dispersed phase. Eachdispersed phase may be characterized by its own average particle sizedistribution in the emulsion, in other words, the average particle sizeof the two independent dispersed phases demonstrate a “bi-modal”distribution.

The first step in the present process is to form a mixture comprisingof, consisting essentially of, or consisting of;

A) 100 parts by weight of a hydrophobic oil,

B) 1 to 1000 parts by weight of a water continuous emulsion having atleast one surfactant.

A) The Hydrophobic Oil

Component A) of the present emulsions contains a hydrophobic oil. Thehydrophobic oil may be selected from an a) an organic oil, b) asilicone, or combinations thereof.

The hydrophobic oil may be selected from various organic compounds ororganic polymers. In this embodiment, the hydrophobic oil phase isconsidered to be an organic oil phase, which means the majority of thisdispersed phase comprises organic compounds or organic polymers. Theorganic oil may be selected from hydrocarbons, oils derived from naturalfats or oils, organic polymers, or mixtures thereof.

Suitable organic oil components include, but are not limited to, naturaloils such as coconut oil; hydrocarbons such as mineral oil andhydrogenated polyisobutene; fatty alcohols such as octyldodecanol;esters such as C12-C15 alkyl benzoate; diesters such as propylenedipelarganate; and triesters, such as glyceryl trioctanoate.

The organic oil composition may be selected from esters having thestructure RCO—OR′ wherein RCO represents the carboxylic acid radical andwherein OR′ is an alcohol residue. Examples of these ester organic oilsinclude isotridecyl isononanoate, PEG-4 diheptanoate, isostearylneopentanoate, tridecyl neopentanoate, cetyl octanoate, cetyl palmitate,cetyl ricinoleate, cetyl stearate, cetyl myristate,coco-dicaprylate/caprate, decyl isostearate, isodecyl oleate, isodecylneopentanoate, isohexyl neopentanoate, octyl palmitate, dioctyl malate,tridecyl octanoate, myristyl myristate, octododecanol, or mixtures ofoctyldodecanol, acetylated lanolin alcohol, cetyl acetate, isododecanol,polyglyceryl-3-diisostearate, or mixtures thereof.

Suitable natural oils include castor oil, lanolin and lanolinderivatives, triisocetyl citrate, sorbitan sesquioleate, C10-18triglycerides, caprylic/capric/triglycerides, coconut oil, corn oil,cottonseed oil, glyceryl triacetyl hydroxystearate, glyceryl triacetylricinoleate, glyceryl trioctanoate, hydrogenated castor oil, linseedoil, mink oil, olive oil, palm oil, castor oil, illipe butter, rapeseedoil, soybean oil, sunflower seed oil, pine oil, tallow, tricaprin,trihydroxystearin, triisostearin, trilaurin, trilinolein, trimyristin,triolein, tripalmitin, tristearin, walnut oil, wheat germ oil,cholesterol, or mixtures thereof.

In one embodiment, the organic oil contains an organic polymer such aspolybutenes or polyisobutylenes, polyacrylates, polystyrenes,polybutadienes, polyamides, polyesters, polyacrylates, polyurethanes,polysulfones, polysulfides, as well as copolymers or terpolymerscontaining these organic polymers, and mixtures of any of these.Representative, non-limiting examples of organic polymers suitable foruse as component A) in the present process include the polybutenes soldby INEOS Oligomers under the trademarked names Indopol® and Panalane®.(INEOS Oligomers, League City, Tex.).

The hydrophobic oil may be selected from various silicone polymers. Inthis embodiment, the hydrophobic oil phase is considered to be asilicone oil phase, which means the majority of this dispersed phasecomprises silicone polymers. As used herein, “silicone” refers to acomposition containing at least one organopolysiloxane.Organopolysiloxanes are polymers containing siloxy units independentlyselected from (R₃SiO_(1/2)), (R₂SiO_(2/2)), (RSiO_(3/2)), or (SiO_(4/2))siloxy units, where R may be any organic group, alternatively R is ahydrocarbon group containing 1 to 30 carbons, alternatively R is analkyl group containing 1 to 12 carbon atoms, or alternatively R ismethyl or phenyl. These siloxy units are commonly referred to as M, D,T, and Q units respectively. Their molecular structures are listedbelow:

These siloxy units can be combined in various manners to form cyclic,linear, or branched structures. The chemical and physical properties ofthe resulting polymeric structures vary depending on the number and typeof siloxy units in the organopolysiloxane.

The silicone composition may contain a single organopolysiloxane, ormixture of various organopolysiloxanes. The silicone composition maycontain silicone fluids, silicone gums, silicone rubbers, siliconeelastomers, silicone resins, or any combinations thereof.

In one embodiment the organopolysiloxane is selected from apolydimethylsiloxane. The polydimethylsiloxane may be a trimethoxy orhydroxy (SiOH) terminated polydimethylsiloxane. Trimethoxy end blockedpolydimethysiloxanes have the formula Me₃SiO(Me₂SiO_(2/2))_(dp)SiMe₃wherein the degree of polymerization (dp) is greater than 1, oralternatively the dp is sufficient to provide a kinematic viscosity thatmay range from 1 to 1,000,000 mm²/s at 25° C., or alternatively from 100to 600,000 mm²/s at 25° C., or alternatively from 1000 to 600,000 mm²/sat 25° C. Representative commercial polydimethylsiloxanes include DowCorning 200 Fluids®, (Dow Corning Corporation, Midland Mich.) availablein varying viscosities from 1 to 600,000 mm²/s at 25° C.

In another embodiment the silicone composition contains a mixture oforganopolysiloxanes that can react with each other to form highermolecular weight organopolysiloxanes. The reaction to form highermolecular weight organopolysiloxanes may be effected by condensation orhydrosilylation of the organopolysiloxanes.

In one embodiment the silicone composition contains organopolysiloxanescomponents that can react via hydrosilylation. In this embodiment, thesilicone component contains;

b¹) an organopolysiloxane having at least two silicon-bonded alkenylgroups per molecule,

b²) an organohydrogensiloxane having at least two SiH groups permolecule, and

b³) a hydrosilylation catalyst,

The organopolysiloxane having at least two silicon-bonded alkenyl groupsper molecule comprises at least two siloxy units represented by theformula R²R_(m)SiO_((4-m)/2) wherein R is an hydrocarbon groupcontaining 1 to 30 carbon atoms, R² is an alkenyl group containing 2 to12 carbon atoms, and m is zero to 2. The R² alkenyl groups of Componentb¹) are exemplified by vinyl, allyl, 3-butenyl, 4-pentenyl, 5-hexenyl,6-heptenyl, 7-octenyl, 8-nonenyl, 9-decenyl, 10-undecenyl,4,7-octadienyl, 5,8-nonadienyl, 5,9-decadienyl, 6,11-dodecadienyl and4,8-nonadienyl.

The R² alkenyl group may be present on any mono, di, or tri siloxy unitin the organopolysiloxane, for example; (R²R₂SiO_(1/2)), (R²RSiO_(2/2)),or (R²SiO_(3/2)); as well as in combination with other siloxy units notcontaining an R² substituent, such as (R₃SiO_(1/2)), (R₂SiO_(2/2)),(RSiO_(3/2)), or (SiO_(4/2)) siloxy units where R is a hydrocarboncontaining 1 to 20 carbons, alternatively an alkyl group containing 1 to12 carbons, alternatively an alkyl group containing 1 to 6 carbons oralternatively methyl; providing there are at least two R² substituentsin the organopolysiloxane. The monovalent hydrocarbon group R havingfrom 1 to 20 carbon atoms is exemplified by alkyl groups such as:methyl, ethyl, propyl, butyl, hexyl, octyl, and decyl; cycloaliphaticgroups such as cyclohexyl; aryl groups such as phenyl, tolyl, and xylyl;and aralkyl groups such as benzyl and phenylethyl.

Component b¹) may be selected from trimethylsiloxy-terminatedpolydimethylsiloxane-polymethylvinylsiloxane copolymers,vinyldimethylsiloxy-terminatedpolydimethylsiloxane-polymethylvinylsiloxane copolymers,trimethylsiloxy-terminatedpolydimethylsiloxane-polymethylhexenylsiloxane copolymers,hexenyldimethylsiloxy-terminatedpolydimethylsiloxane-polymethylhexenylsiloxane copolymers,trimethylsiloxy-terminated polymethylvinylsiloxane polymers,trimethylsiloxy-terminated polymethylhexenylsiloxane polymers,vinyldimethylsiloxy-terminated polydimethylsiloxane polymers,hexenyldimethylsiloxy-terminated polydimethylsiloxane polymers, or anycombination thereof, each having a degree of polymerization of from 10to 300, or alternatively having a viscosity at 25° C. of 10 to 1000mPa·s.

Component b²) is an organohydrogensiloxane having an average of greaterthan two silicon bonded hydrogen atoms per molecule. As used herein, anorganohydrogensiloxane is any organopolysiloxane containing asilicon-bonded hydrogen atom (SiH).

Organohydrogensiloxanes are organopolysiloxanes having at least one SiHcontaining siloxy unit, that is at least one siloxy unit in theorganopolysiloxane has the formula (R₂HSiO_(1/2)), (RHSiO_(2/2)), or(HSiO_(3/2)). Thus, the organohydrogensiloxanes useful in the presentinvention may comprise any number of (R₃SiO_(1/2)), (R₂SiO_(2/2)),(RSiO_(3/2)), (R₂HSiO_(1/2)), (RHSiO_(2/2)), (HSiO_(3/2)) or (SiO_(4/2))siloxy units, providing there are on average at least two SiH siloxyunits in the molecule. Component b²) can be a single linear or branchedorganohydrogensiloxane or a combination comprising two or more linear orbranched organohydrogensiloxanes that differ in at least one of thefollowing properties; structure, viscosity, average molecular weight,siloxane units, and sequence. There are no particular restrictions onthe molecular weight of the organohydrogensiloxane, but typically theviscosity of the organohydrogensiloxane at 25° C. is from 3 to 10,000mPa·s, alternatively 3 to 1,000 mPa·s, or alternatively 10 to 500 mPa·s.

The amount of SiH units present in the organohydrogensiloxane may vary,providing there are at least two SiH units per organohydrogensiloxanemolecule. The amount of SiH units present in the organohydrogensiloxaneis expressed herein as % SiH which is the weight percent of hydrogen inthe organohydrogensiloxane. Typically, the % SiH varies from 0.01 to10%, alternatively from 0.1 to 5%, or alternatively from 0.5 to 2%.

The organohydrogensiloxane may comprise the average formula;

(R³ ₃SiO_(1/2))_(a)(R⁴ ₂SiO_(2/2))_(b)(R⁴HSiO_(2/2))_(c) wherein

R³ is hydrogen or R⁴,

R⁴ is a monovalent hydrocarbon group having from 1 to 10 carbon atoms

-   -   a≧2,    -   b≧0, alternatively b=1 to 500, alternatively b=1 to 200,    -   c≧2, alternatively c=2 to 200, alternatively c=2 to 100.

R⁴ may be a substituted or unsubstituted aliphatic or aromatichydrocarbyl. Monovalent unsubstituted aliphatic hydrocarbyls areexemplified by, but not limited to alkyl groups such as methyl, ethyl,propyl, pentyl, octyl, undecyl, and octadecyl and cycloalkyl groups suchas cyclohexyl. Monovalent substituted aliphatic hydrocarbyls areexemplified by, but not limited to halogenated alkyl groups such aschloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl. The aromatichydrocarbon group is exemplified by, but not limited to, phenyl, tolyl,xylyl, benzyl, styryl, and 2-phenylethyl.

The amounts of components b¹) and b²) used may vary, but typically theamounts of components b¹) and b²) are selected so as to provide a molarratio of the alkenyl groups to SiH in the composition that is greaterthan 1.

Component b³) is a hydrosilylation catalyst. The hydrosilylationcatalyst may be any suitable Group VIII metal based catalyst selectedfrom a platinum, rhodium, iridium, palladium or ruthenium. Group VIIIgroup metal containing catalysts useful to catalyze curing of thepresent compositions can be any of those known to catalyze reactions ofsilicon bonded hydrogen atoms with silicon bonded unsaturatedhydrocarbon groups. The preferred Group VIII metal for use as a catalystto effect cure of the present compositions by hydrosilylation is aplatinum based catalyst. Some preferred platinum based hydrosilylationcatalysts for curing the present composition are platinum metal,platinum compounds and platinum complexes. Suitable platinum catalystsare described in U.S. Pat. No. 2,823,218 (commonly referred to as“Speier's catalyst) and U.S. Pat. No. 3,923,705. The platinum catalystmay be “Karstedt's catalyst”, which is described in Karstedt's U.S. Pat.Nos. 3,715,334 and 3,814,730. Karstedt's catalyst is a platinum divinyltetramethyl disiloxane complex typically containing about one-weightpercent of platinum in a solvent such as toluene. Alternatively theplatinum catalyst may be a reaction product of chloroplatinic acid andan organosilicon compound containing terminal aliphatic unsaturation, asdescribed in U.S. Pat. No. 3,419,593. Alternatively, the hydrosilylationcatalyst is a neutralized complex of platinum chloride and divinyltetramethyl disiloxane, as described in U.S. Pat. No. 5,175,325.

The amounts of catalyst b³) used may vary, but typically an amount isused to effect the hydrosilylation reaction. When the catalyst is a Ptcompound, typically a sufficient amount of the compound is added toprovide 2 to 500 ppm of Pt in the silicone composition.

Additional components may be added to the hydrosilylation reaction. Forexample, heptamethyltrisiloxysilane may be added as an endblocker tocontrol molecular weight of the organopolysiloxane product.

In one embodiment the silicone composition contains organopolysiloxanescomponents that can react via condensation. In this embodiment, thesilicone composition contains an organopolysiloxane having at least twosiloxy units with a substituent capable of reacting via condensation.Suitable substitutes on the siloxy units of the organopolysiloxanesinclude silanol, alkoxy, acetoxy, oxime functional groups. In thisembodiment, the silicone composition will further contain a catalystknown in the art for enhancing condensation cure of organopolysiloxanessuch as a tin or titanium catalyst. In a further embodiment, theorganopolysiloxane is a silanol endblocked polydimethylsiloxane having akinematic viscosity that may range from 1 to 100,000 mm²/s at 25° C., oralternatively from 1 to 10,000 mm²/s at 25° C. Representative commercialsilanol endblocked polydimethylsiloxanes include; XIAMETER® OHX-40002000cs, XIAMETER® OHX-4010 4000cs, XIAMETER® OHX-4012 6000cs, XIAMETER®OHX-4040 14000cs, XIAMETER® PMX-0930 Silanol fluid, DOW CORNING® 3-0133Polymer, DOW CORNING® 3-0213 Polymer, DOW CORNING® 3-0113 Polymer, DOWCORNING® 3-0084 Polymer, and DOW CORNING® 2-1273 Fluid.

In one embodiment the silicone composition contains organopolysiloxaneshaving at least one siloxy unit substituted with an organofunctionalgroup. The organofunctional organopolysiloxanes useful in the presentprocess are characterized by having at least one of the R groups in theformula R_(n)SiO_((4-n)/2) be an organofunctional group. Representativenon-limiting organofunctional groups include; amino, amido, epoxy,mercapto, polyether (polyoxyalkylene) groups, and any mixture thereof.The organofunctional group may be present on any siloxy unit having an Rsubstituent, that is, they may be present on any (R₃SiO_(0.5)), (R₂SiO),or (RSiO_(1.5)) unit.

In a further embodiment, the organofunctional group is an amino group.Amino-functional groups may be designated in the formulas herein asR^(N) and is illustrated by groups having the formula; —R¹NHR², —R¹NR₂², or —R¹NHR¹NHR², wherein each R¹ is independently a divalenthydrocarbon group having at least 2 carbon atoms, and R² is hydrogen oran alkyl group. Each R¹ is typically an alkylene group having from 2 to20 carbon atoms. Some examples of suitable amino-functional hydrocarbongroups are; —CH₂CH₂NH₂, —CH₂CH₂CH₂NH₂, —CH₂CHCH₃NH, —CH₂CH₂CH₂CH₂NH₂,—CH₂CH₂CH₂CH₂CH₂NH₂, —CH₂CH₂CH₂CH₂CH₂CH₂NH₂, —CH₂CH₂NHCH₃,—CH₂CH₂CH₂NHCH₃, —CH₂(CH₃)CHCH₂NHCH₃, —CH₂CH₂CH₂CH₂NHCH₃,—CH₂CH₂NHCH₂CH₂NH₂, —CH₂CH₂CH₂NHCH₂CH₂NH₂, —CH₂CH₂CH₂NHCH₂CH₂CH₂NH₂,—CH₂CH₂CH₂CH₂NHCH₂CH₂CH₂CH₂NH₂, —CH₂CH₂NHCH₂CH₂NHCH₃,—CH₂CH₂CH₂NHCH₂CH₂CH₂NHCH₃, —CH₂CH₂CH₂CH₂NHCH₂CH₂CH₂CH₂NHCH₃, and—CH₂CH₂NHCH₂CH₂NHCH₂CH₂CH₂CH₃.

Representative commercial aminofunctional organopolysiloxanes include;XIAMETER® OFX-8040 Fluid, XIAMETER® OHX-8600 Fluid, XIAMETER® OHX-8630Fluid, XIAMETER® OHX-8803 Fluid, DOW CORNING® AP-8087 Fluid, DOWCORNING® 2-8040 Polymer, DOW CORNING® 8566 Polymer, DOW CORNING® 8600HYDROPHILIC SOFTENER, and DOW CORNING® 8803 Polymer.

B) The Water Continuous Emulsion

Component B) in the present process is a water continuous emulsion.Component B) may be a single water continuous emulsion, or a combinationof water continuous emulsions.

The water continuous emulsion(s) useful as component B) in the presentprocess contains at least one surfactant. The surfactant may vary, buttypically is chosen from those surfactants that enhance the formation ofwater continuous emulsions. The surfactant may be an anionic surfactant,cationic surfactant, nonionic surfactant, amphoteric surfactant, or amixture of any of these surfactants.

Representative examples of suitable anionic surfactants include alkalimetal, amine, or ammonium salts of higher fatty acids, alkylarylsulphonates such as sodium dodecyl benzene sulfonate, long chain fattyalcohol sulfates, olefin sulfates and olefin sulfonates, sulfatedmonoglycerides, sulfated esters, sulfonated ethoxylated alcohols,sulfosuccinates, alkane sulfonates, phosphate esters, alkylisethionates, alkyl taurates, and alkyl sarcosinates.

Representative examples of suitable cationic surfactants includealkylamine salts, quaternary ammonium salts, sulphonium salts, andphosphonium salts. Representative examples of suitable nonionicsurfactants include condensates of ethylene oxide with long chain fattyalcohols or fatty acids such as a C₁₂₋₁₆ alcohol, condensates ofethylene oxide with an amine or an amide, condensation products ofethylene and propylene oxide, esters of glycerol, sucrose, sorbitol,fatty acid alkylol amides, sucrose esters, fluoro-surfactants, and fattyamine oxides. Representative examples of suitable amphoteric surfactantsinclude imidazoline compounds, alkylaminoacid salts, and betaines.

Representative examples of suitable commercially available nonionicsurfactants include polyoxyethylene fatty alcohols sold under thetradename BRIJ® by Croda (ICI Surfactants), Wilmington, Del. Someexamples are BRIJ® 35 Liquid, an ethoxylated alcohol known aspolyoxyethylene (23) lauryl ether, and BRIJ® 30, another ethoxylatedalcohol known as polyoxyethylene (4) lauryl ether. Some additionalnonionic surfactants include ethoxylated alcohols sold under thetrademark TERGITOL® by The Dow Chemical Company, Midland, Mich. Someexample are TERGITOL® TMN-6, an ethoxylated alcohol known as ethoxylatedtrimethylnonanol; and various of the ethoxylated alcohols, i.e., C₁₂-C₁₄secondary alcohol ethoxylates, sold under the trademarks TERGITOL®15-S-5, TERGITOL® 15-S-12, TERGITOL® 15-S-15, and TERGITOL® 15-S-40.Lutensol supplied by BASF in the series of Lutensol XP known asethoxylated, C10-Guerbet alcohol and Lutensol TO known as ethoxylated,iso-C13 alcohol may also be used.

When mixtures containing nonionic surfactants are used, one nonionicsurfactant may have a low Hydrophile-Lipophile Balance (HLB) and theother nonionic surfactant may have a high HLB, such that the twononionic surfactants have a combined HLB of 11-15, alternatively acombined HLB of 12.5-14.5.

The water continuous emulsion may be selected from those considered inthe art to be a “macro” or “micro” emulsion. In other words, the averageparticle size of the water continuous emulsion may vary from 0.001 to1000 μm, alternatively from 0.01 to 20 μm, or alternatively from 0.02 to10 μm.

In one specific embodiment, the water continuous emulsion is amicroemulsion having an average particle size of less than 100 nm.

In one embodiment, the water continuous emulsion may be selected from a“mechanical emulsion”. As used herein, mechanical emulsions refer tothose emulsion in the art produced by using mechanical energy (such asfrom high shearing forces). The mechanical emulsions may be eitherorganic or silicone.

In one embodiment, the water continuous emulsion may be considered an“emulsion polymer”, in other words, an emulsion formed by emulsionpolymerization techniques. The emulsion polymer may be either organic orsilicone.

In a further embodiment, the organic emulsion may be selected from thoseemulsions considered in the art to be a “latex”. A latex is a stableemulsion of a polymer or mixture of polymers, which may be eithernatural or synthetic. The latex may be organic or silicone.

In one embodiment, the water continuous emulsion is an organic emulsion.In this embodiment, the dispersed phase in the emulsion contains atleast one organic oil, such as those described above as component A).

In a further embodiment, the organic emulsion may be selected from alatex. Representative, non-limiting suitable synthetic organic latticesinclude; styrene, styrene-butadiene, acrylonitrile,acrylonitrile-butadiene, acrylics, polyvinyl acetate, polyacrylate,polyurethane, epoxy, and alkyds. Representative, non-limiting examplesof commercially available lattices useful as the water continuousemulsion in the present process include the series of lattices sold byBASF under the tradename of Joncryl®, such as Joncryl® 77 (BASF).

In another embodiment, the organic emulsion is an emulsion of a naturaloil, such as pine oil. A representative, non-limiting example ofcommercially available natural oil emulsions useful as the watercontinuous emulsion in the present process includes Pinesol®. Theorganic emulsion may also be an emulsion of a wax, such as Michem® WaxEmulsion. The organic emulsion may also be a PTFE dispersion.

In one embodiment, the water continuous emulsion is a silicone emulsion.In this embodiment, the dispersed phase in the emulsion contains atleast one organopolysiloxane, such as the organopolysiloxanes asdescribed above for use as component A).

In a further embodiment, the silicone emulsion is a mechanical emulsion.Representative, non-limiting suitable examples of suitable siliconeemulsions produced by mechanical techniques are taught in U.S. Pat. No.6,395,790, which is incorporated herein by reference.

In a further embodiment, the emulsion polymer is a silicone emulsionpolymer. The silicone emulsion polymer. Representative, non-limitingsuitable examples of suitable silicone emulsions produced by emulsionpolymerization techniques suitable for use in the present process aretaught in; U.S. Pat. No. 2,891,920, U.S. Pat. No. 3,294,725, U.S. Pat.No. 5,661,215, U.S. Pat. No. 5,817,714, and U.S. Pat. No. 6,316,541,which are incorporated herein by reference. Representative, non-limitingcommercial products suitable as silicone emulsions produced by emulsionpolymerization techniques include; Dow Corning® HV-490, Dow Corning®929, Dow Corning® 939, Dow Corning 949, Dow Corning 1391, Dow Corning2-1865, Dow Corning® 2-1870, Dow Corning® 2-1938, DC 2-8194, and DowCorning® 2-8194 (Dow Corning Corporation, Midland Mich.).

In one embodiment, the water continuous emulsion may be prepared usingsuspension polymerization techniques. The suspension emulsions may beeither organic or silicone.

In a further embodiment, the water continuous emulsion prepared usingsuspension polymerization techniques is a silicone emulsion polymer.Representative, non-limiting examples of suitable silicone emulsionsproduced by suspension polymerization techniques suitable for use in thepresent process are taught in; U.S. Pat. No. 4,618,645, U.S. Pat. No.6,248,855, and U.S. Pat. No. 6,395,790. Representative, non-limitingcommercial products suitable as silicone emulsions produced bysuspension polymerization techniques include; Dow Corning® 1997, DowCorning® HMW 2220, Xiameter® MEM 1785 Emulsion, Dow Corning® 1788Emulsion (Dow Corning Corporation, Midland Mich.).

Mixing in step (I) can be accomplished by any method known in the art toeffect mixing of high viscosity materials. The mixing may occur eitheras a batch, semi-continuous, or continuous process. Mixing may occur,for example using, batch mixing equipments with medium/low shear includechange-can mixers, double-planetary mixers, conical-screw mixers, ribbonblenders, double-arm or sigma-blade mixers; batch equipments withhigh-shear and high-speed dispersers include those made by Charles Ross& Sons (NY), Hockmeyer Equipment Corp. (NJ); batch equipments with highshear actions include Banbury-type (CW Brabender Instruments Inc., NJ)and Henschel type (Henschel mixers America, TX). Illustrative examplesof continuous mixers/compounders include extruders single-screw,twin-screw, and multi-screw extruders, co-rotating extruders, such asthose manufactured by Krupp Werner & Pfleiderer Corp (Ramsey, N.J.), andLeistritz (NJ); twin-screw counter-rotating extruders, two-stageextruders, twin-rotor continuous mixers, dynamic or static mixers orcombinations of these equipments.

The temperature and pressure at which the mixing of step I occurs is notcritical, but generally is conducted at ambient temperature andpressures. Typically, the temperature of the mixture will increaseduring the mixing process due to the mechanical energy associated whenshearing such high viscosity materials.

Typically 1 to 1000 parts by weight of the water continuous emulsion aremixed for every 100 parts by weight of component A) in the step Imixture, alternatively from 5 to 500 parts per 100 parts by weight ofcomponent A) in the step I mixture, or alternatively from 5 to 100 partsper 100 parts by weight of component A) the step I mixture.

In one embodiment of the present process, step I involves forming amixture consisting essentially of;

A) 100 parts by weight of a hydrophobic oil,

B) 1 to 1000 parts by weight of a water continuous emulsion having atleast one surfactant. In this embodiment, the mixture formed in step I)is “essentially free” from any other surfactant compounds or componentsother than components A) and B). As used herein, “essentially free”means no other surfactant compounds are added to the mixture formed instep I), other than the surfactant(s) present in B) the water continuousemulsion.

Step II) of the process involves admixing additional quantities of thewater continuous emulsion and/or water to the mixture from step I) toform a bi-modal emulsion.

The amount of the additional quantities of the water continuous emulsionand/or water used in step II) may vary depending on the selection ofcomponents A) and B). Typically the amount of additional watercontinuous emulsion and/or water admixed in step II) of the presentprocess may vary from 1 to 1000 parts by weight of the step I mixture,alternatively from 5 to 500 parts per 100 parts by weight, oralternatively from 5 to 100 parts per 100 parts by weight.

In step II) of the present process, additional quantities of the watercontinuous emulsion may be used alone, or alternatively be combined withvarying quantities of water. Alternatively, additional quantities ofwater may be added alone without any additional quantities of the watercontinuous emulsion. The selection of using additional quantities of thewater continuous emulsion alone, in combination with varying amounts ofwater, or water alone will depend on the initial selection of the watercontinuous emulsion and the desired physical properties of the resultingbi-modal emulsion. For example, high solids bi-modal emulsions may beprepared with only the addition of the water continuous emulsion.Conversely, low solids bi-modal emulsions may require the addition ofwater as well.

The water continuous emulsion and/or water is added to the mixture fromstep I at such a rate, with additional mixing, so as to form an emulsionof the mixture of step I. The water continuous emulsion added to themixture from step I may be done in incremental portions, whereby eachincremental portion comprises less than 50 weight % of the mixture fromstep I, alternatively 25 weight % of the mixture from step I, and eachincremental portion of water continuous emulsion is added successivelyto the previous after the dispersion of the previous incremental portionof water continuous emulsion, wherein sufficient incremental portions ofwater continuous emulsion are added to form the bi-modal emulsion.

The number of incremental portions of the water continuous emulsionand/or water added to the mixture from step I may vary, but typically atleast 2, alternatively, at least 3 incremental portions are added.

Mixing in step (II) can be accomplished by any method known in the artto effect mixing of high viscosity materials and/or effect the formationof an emulsion. The mixing may occur either as a batch, semi-continuous,or continuous process. Any of the mixing methods as described for step(I), may be used to effect mixing in step (II). Alternatively, mixing instep (II) may also occur via those techniques known in the art toprovide high shear mixing to effect formation of emulsions.Representative of such high shear mixing techniques include; high speedstirrers, homogenizers, Sonolators®, microfluidizers, Ross mixers,Eppenbach colloid mills, Flacktek Speedmixers, and other similar sheardevices.

Optionally, the emulsion formed in step (II) may be further shearedaccording to step (III) to reduce particle size and/or improve long termstorage stability. The shearing may occur by any of the mixingtechniques discussed above.

The present invention further relates to the bi-modal water continuousemulsions obtained using the present process.

The water continuous emulsions prepared by the process of the presentdisclosure may be characterized by their bi-modal particle sizedistribution. The particle size may be determined by laser diffractionof the emulsion. Suitable laser diffraction techniques are well known inthe art. The particle size is obtained from a particle size distribution(PSD). The PSD can be determined on a volume, surface, length basis. Thevolume particle size is equal to the diameter of the sphere that has thesame volume as a given particle. The term Dv, as used herein, representsthe average volume particle size of the dispersed particles. Dv 50 isthe particle size measured in volume corresponding to 50% of thecumulative particle population. In other words if Dv 50=10 μm, 50% ofthe particle have an average volume particle size below 10 μm and 50% ofthe particle have a volume average particle size above 10 μm. Dv 90 isthe particle size measured in volume corresponding to 90% of thecumulative particle population. Mode 1 is the median of the distributionof the first population of particles within a bimodal particledistribution and Mode 2 is the median of the second.

In some instances, it may be necessary to conduct two separateevaluations of particle size, especially when the particle sizesdistributions of the resulting bi-modal emulsions exhibit a widevariation in size. In these instances a Malvern-Mastersizer® 2000 may beused to obtain particle size distributions in the range 0.5 to 1000 μm,while a Microtrac-Nanotrac® may be used to measure particle sizedistributions in the ranges less than 0.5 μm.

The average volume particle size of the dispersed particles in theoil/water emulsions is between 0.001 μm and 1000 μm; or between 0.01 μmand 20 μm; or between 0.02 μm and 10 μm.

Alternatively, the average volume particle size of each of the uniquedispersed phases (that is the first dispersed phase, and the seconddispersed phase), may be reported. The average volume particle size ofthe first dispersed particles in the oil/water emulsions is between 0.1μm and 500 μm; or between 0.1 μm and 100 μm; or between 0.2 μm and 30μm. The average volume particle size of the second dispersed particlesin the oil/water emulsions is between 0.1 μm and 500 μm; or between 0.1μm and 100 μm; or between 0.2 μm and 30 μm.

While not wishing to be bound by any theory, the present inventorsbelieve particle size distribution of the second dispersed phase resultsfrom the emulsification of the hydrophobic oil, while particle sizedistribution of the first dispersed phase results from the particlesoriginating from the water continuous emulsion used in the presentprocess. However, there may be certain instances where the two overlapsufficiently that a bi-modal distribution is not observable using theparticle size determination techniques described above.

The bimodal particle size distribution may also be observed usingoptical microscopy techniques.

In another embodiment, the bi-modal emulsions may be considered as a“high solids” emulsion, wherein the bi-modal emulsion contains at least75% by weight of components A) and B), alternatively the bi-modalemulsion contains at least 80% by weight of components A) and B),alternatively the bi-modal emulsion contains at least 85% by weight ofcomponents A) and B), alternatively the bi-modal emulsion contains atleast 90% by weight of components A) and B).

In a further embodiment, the “high solids” bi-modal emulsion remainpourable. Thus, the bi-modal emulsions may have a viscosity less than600,000 cP, alternatively less than 200,000 cP, or alternatively lessthan 100,000 cP, as measured at 25° C.

In another embodiment, the total surfactant concentration in thebi-modal emulsion is less than 4.0 weight %, alternatively less than 1.0weight %, or alternatively less than 0.2 weight %.

In another embodiment, the bi-modal silicone emulsions produced by thepresent process contains less than 1.0 weight % cyclosiloxanes, oralternatively containing less than 0.5 weight % cyclosiloxanes, oralternatively containing less than 0.1 weight % cyclosiloxanes.

The present bi-modal emulsions are useful a variety of applicationswhere it is desirable to provide pourable water based organic orsilicone materials having a high solids content. Such applicationsinclude various coating applications. The present emulsions may also bebeneficial in personal care applications.

EXAMPLES

The following examples are included to demonstrate preferred embodimentsof the invention. It should be appreciated by those of skill in the artthat the techniques disclosed in the examples which follow representtechniques discovered by the inventor to function well in the practiceof the invention, and thus can be considered to constitute preferredmodes for its practice. However, those of skill in the art should, inlight of the present disclosure, appreciate that many changes can bemade in the specific embodiments which are disclosed and still obtain alike or similar result without departing from the spirit and scope ofthe invention. All percentages are in wt. %. All measurements wereconducted at 23° C. unless indicated otherwise.

Example 1 Emulsification of 100K PDMS with 949 Emulsion

20 g of 100,000 centistoke (cSt.) Dow Corning® 200 Fluid, apolydimethylsiloxane (PDMS) fluid, was weighed into a Max 40 cupfollowed by 2.5 g of Dow Corning® 949 Cationic Emulsion, which is anaqueous emulsion containing 35% silicone aminofunctional polymer. Thecup was closed and placed inside a DAC-150 SpeedMixer® and the cup wasspun at maximum speed (3450 RPM) for 30 seconds. The cup was opened andthe walls of the cup were scraped with a spatula and the cup was spunagain at maximum speed for 30 seconds. 3 g of 949 Cationic Emulsion wasweighed into the cup and the cup was spun for 30 seconds atapproximately 2500 RPM. 4.5 g of 949 Cationic Emulsion was added and thecup was again spun for 30 seconds at approximately 2500 RPM. Theresulting emulsion consisted of an aqueous oil-in-water (o/w) emulsionof silicone polymer having a total silicone content of approximately78.3 percent. On a dry basis, this emulsions contained approximately 85percent PDMS and 15 percent amino-functional PDMS. Particle size of theemulsion was determined using a Malvern Mastersizer® 2000 and MicrotracNanotrac® and the results were:

Dv50=22.24 μm, Dv90=54.27 μm, Mode 1=0.122 μm, Mode 2=22.24 μm.

Example 2 Emulsification of 600K PDMS with 8170 Microemulsion

43.1 g of 100,000 centistoke (cSt.) Dow Corning® 200 Fluid, apoly(dimethylsiloxane) fluid, was weighed into a Max 40 cup followed by6.99 g of Dow Corning® CE-8170 AF Microemulsion, which is an aqueousemulsion containing 20% silicone aminofunctional polymer. The cup wasclosed and placed inside a DAC-150 SpeedMixer® and the cup was spun atmaximum speed (3450 RPM) for 30 seconds. The cup was opened and thewalls of the cup were scraped with a spatula. The cup was spun again atmaximum speed for 30 seconds. 6.59 g of 8170 Cationic Emulsion wasweighed into the cup and the cup was spun for 30 seconds atapproximately 2500 RPM. The resulting emulsion consisted of an aqueousoil-in-water (o/w) emulsion of silicone polymer having a total siliconecontent of approximately 80.78 percent. On a dry basis, this emulsionscontained approximately 91 percent PDMS and 9 percent amino-functionalPDMS. Particle size of the emulsion was determined using a MalvernMastersizer® 2000 and Microtrac Nanotrac® and the results were asfollows:

Dv50=22.894 μm, Dv90=52.195 μm, Mode 1=0.0941 μm, Mode 2=22.984 μm.

Example 3 Emulsification of 100K PDMS with 1785 Emulsion

20 g of 100,000 centistoke (cSt.) Dow Corning® 200 Fluid, apoly(dimethylsiloxane) fluid, was weighed into a Max 40 cup followed by5 g of Xiameter® MEM 1785 Emulsion which is a 60% aqueous emulsion ofhigh molecular weight OH functional poly(dimethylsiloxane). The cup wasclosed and placed inside a DAC-150 SpeedMixer® and the cup was spun atmaximum speed (3450 RPM) for 30 seconds. The cup was opened and thewalls of the cup were scraped with a spatula and the cup was spun againat maximum speed for 30 seconds. 3 g of 1785 Emulsion was weighed intothe cup and the cup was spun for 30 seconds at approximately 2500 RPM.4.5 g of 1785 Emulsion was added and the cup was again spun for 30seconds at approximately 2500 RPM. The resulting emulsion consisted ofan aqueous oil-in-water (o/w) emulsion of silicone polymer having atotal silicone content of approximately 86.7 percent. On a dry basis,this emulsions contained approximately 77 percent 100,000 cSt PDMS aslarge particles and 23 percent high molecular weight, OH functional PDMSas smaller particles. Particle size of the emulsion was determined usinga Malvern Mastersizer®. The particle size curve showed two distinctpeaks, one centered at 6.5 μm and another that was centered at 35 μm.Particle size as calculated by the instrument was as follows: Dv50=21.66μm, Dv90=85.31 μm, Mode 1=0.67 μm, Mode 2=33.877 μm.

Example 4 Step-Growth Emulsion Polymerization with 939 Emulsion

20.0 g of a dimethylvinyl-ended polydimethylsiloxane polymer having akinematic viscosity of approximately 55,000 cSt was weighed into a Max40 cup followed by 0.41 g of a mixture made by adding 0.729 g ofheptamethyltrisiloxane to 24.721 g of a trimethylsiloxy-endeddimethyl-methylhydrogen polysiloxane copolymer having a silicon-bondedhydrogen content of 0.18 percent by weight and having a kinematicviscosity of approximately 10 cSt. This was followed by adding 1 dropfrom a small pipet (approximately 0.1 g) of Syloff® 4000 Catalyst (Ptcatalyst). The cup was closed and the cup was spun in a DAC-150SpeedMixer® for 20 seconds at maximum speed. 2.0 g of Dow Corning® 939Cationic Emulsion was added next and the cup was closed and spun for 30seconds at maximum speed. The walls of the cup were scraped with aspatula and the cup was spun again for 30 seconds at maximum speed. 5.0g of water was added in 2 equal increments with the cup being spun for25 seconds at maximum speed after each increment was added. Particlesize was measured with a Malvern Mastersizer® 2000 and MicrotracNanotrac®. Particle size as calculated by the instrument was as follows:

Dv50=13.39 μm, Dv90=25.70 μm, Mode 1=0.301 μm, Mode 2=11.314 μm.

This composition consisted of an approximately 77 percent siliconeaqueous emulsion. The silicone phase in this emulsion was made up ofapproximately 97 percent high viscosity polydimethylsiloxane (largeparticles) and 3 percent aminofunctional polydimethylsiloxane (smallerparticles).

Example 5 Step-Growth Emulsion Polymerization with 939 Emulsion

20.0 g of a dimethylvinyl-ended polydimethylsiloxane polymer having akinematic viscosity of approximately 55,000 cSt was weighed into a Max40 cup followed by 0.41 g of a mixture made by adding 0.729 g ofheptamethyltrisiloxane to 24.721 g of a trimethylsiloxy-endeddimethyl-methylhydrogen polysiloxane copolymer having a silicon-bondedhydrogen content of 0.18 percent by weight and having a kinematicviscosity of approximately 10 cSt. This was followed by adding 1 dropfrom a small pipet (approximately 0.1 g) of Syloft® 4000 Catalyst (Ptcatalyst). The cup was closed and the cup was spun in a DAC-150SpeedMixer® for 20 seconds at maximum speed. 1.0 g of Dow Corning® 939Cationic Emulsion was added next and the cup was closed and spun for 30seconds at maximum speed. Inspection of the contents of the cup revealedthat the composition had not inverted. In other words, silicone polymerwas the continuous phase. 1.0 g of additional Dow Corning 939 CationicEmulsion was added and the cup was closed and spun for 30 seconds atmaximum speed. The composition in the cup inverted into a water-outemulsion at this stage. The walls of the cup were scraped with a spatulaand the cup was spun again for 30 seconds at maximum speed. 8.0 g of DowCorning® 939 Emulsion was added in 3 equal increments with the cup beingspun for 25 seconds at maximum speed after each increment was added.Particle size was measured with a Malvern Mastersizer® 2000 andMicrotrac Nanotrac®. Particle size as calculated by the instrument wasas follows: Dv50=10.94 μm, Dv90=19.61 μm, Mode 1=0.30 μm, Mode 2=10.41μm.

This composition consisted of an approximately 78 percent siliconeaqueous emulsion. The silicone phase in this emulsion was made up ofapproximately 85 percent high viscosity polydimethylsiloxane (largeparticles) and 15 percent aminofunctional polydimethylsiloxane (smallerparticles).

Example 6 Step-Growth Emulsion Polymerization with 1788 Emulsion

20.0 g of a dimethylvinyl-ended polydimethylsiloxane polymer having akinematic viscosity of approximately 55,000 cSt was weighed into a Max40 cup followed by 0.40 g of a mixture made by adding 0.729 g ofheptamethyltrisiloxane to 24.721 g of a trimethylsiloxy-endeddimethyl-methylhydrogen polysiloxane copolymer having a silicon-bondedhydrogen content of 0.18 percent by weight and having a kinematicviscosity of approximately 10 cSt. This was followed by adding 1 dropfrom a small pipet (approximately 0.1 g) of Syloff® 4000 Catalyst (Ptcatalyst). The cup was closed and the cup was spun in a DAC-150SpeedMixer® for 20 seconds at maximum speed. 2.0 g of Dow Corning® 1788Emulsion (a 49 percent emulsion of high viscosity OH functionalpolydimethylsiloxane) was added next and the cup was closed and spun for30 seconds at maximum speed. The walls of the cup were scraped with aspatula and the cup was spun again for 30 seconds at maximum speed. 8.0g of Dow Corning® 1788 Emulsion was added in 2 equal increments with thecup being spun for 25 seconds at maximum speed after each increment wasadded. Particle size was measured with a Malvern Mastersizer® 2000 andMicrotrac Nanotrac®. Particle size as calculated by the instrument wasas follows: Dv50=16.87 μm, Dv90=32.21 μm, Mode 1=0.30 μm, Mode 2=11.01μm.

This composition consisted of an approximately 83 percent siliconeaqueous emulsion. The silicone phase in this emulsion was made up ofapproximately 81 percent high viscosity polydimethylsiloxane in the formof large particles and 19 percent high viscosity polydimethylsiloxane inthe form of smaller particles.

Example 7 Organic Oil with 1785 Silicone Emulsion

20.0 g of Indopol® H-300 polybutene having a kinematic viscosity of 630cSt (100 C) was weighed into a Max 40 cup followed by 2 g of Xiameter®MEM 1785 Emulsion which is a 60% aqueous emulsion of high molecularweight OH functional polydimethylsiloxane. The cup was closed and placedinside a DAC-150 SpeedMixer® and the cup was spun at maximum speed (3500RPM) for 30 seconds. The cup was opened and the walls of the cup werescraped with a spatula and the cup was spun again at maximum speed for30 seconds. 4 g of 1785 Emulsion was weighed into the cup and the cupwas spun for 30 seconds at approximately 2500 RPM. Another 4 g of 1785Emulsion was added and the cup was again spun for 30 seconds atapproximately 2500 RPM. The resulting emulsion consisted of an aqueousoil-in-water (o/w) emulsion of polybutene and high viscositypolydimethylsiloxane having a total polymer content of approximately86.7 percent. On a dry basis, this emulsions contained approximately 77percent polybutene in larger particles and 23 percent high molecularweight, OH functional PDMS in smaller particles. Particle size of theemulsion was determined using a Malvern Mastersizer® 2000. The particlesize curve showed two distinct peaks, one centered at about 0.7 μm andanother that was centered at about 10 μm. Particle size as calculated bythe instrument was as follows: Dv50=5.57 μm, Dv90=18.02 μm, Mode 1=0.768μm, Mode 2=11.601 μm.

Example 8 Silicone Oil with Pinesol® Organic Oil Emulsion

20 g of an OH functional polydimethylsiloxane polymer having a viscosityof 50,000 mPa-sec was weighed into a Max 40 cup followed by 0.5 g ofPinesol® Cleaner, which is a microemulsion of 8.7 percent pine oil inwater with surfactants and other ingredients. The cup was closed andplaced inside a DAC-150 SpeedMixer® and the cup was spun at maximumspeed (3450 RPM) for 30 seconds. The cup was opened and the walls of thecup were scraped with a spatula and the cup was spun again at maximumspeed for 30 seconds. The resulting emulsion was diluted with additionalPinesol® Cleaner in two 2.5 g increments while the cup was spun for 20seconds at maximum speed after each dilution. This emulsion containedapproximately 80 percent dispersed phase of silicone and pine oil. Thedispersed phase was made up of approximately 98 percent silicone polymerand 2 percent pine oil. Particle size of the emulsion was determinedusing a Malvern Mastersizer® 2000 and Microtrac Nanotrac®. Particle sizeas calculated by the instrument was as follows:

Dv50=3.03 μm, Dv90=4.29 μm, Mode 1=0.102 μm, Mode 2=3.02 μm.

Example 9 Emulsification of 600K PDMS and Joncryl® 77

42.83 g of 600,000 centistoke (cSt.) Dow Corning® 200 Fluid, apolydimethylsiloxane (PDMS) fluid, was weighed into a Max 40 cupfollowed by 8.60 g of Joncryl® 77, which is an aqueous acrylic emulsion(BASF) having a non-volatile content of 46 wt %. The cup was closed andplaced inside a DAC-150 SpeedMixer® and the cup was spun at maximumspeed (3450 RPM) for 45 seconds. The cup was opened and the walls of thecup were scraped with a spatula and the cup was spun again at maximumspeed for 45 seconds. An additional 8.60 g of Joncryl® 77 CationicEmulsion was weighed into the cup and the cup was spun for 45 seconds atapproximately 3450 RPM. The walls of the cup were scraped with a spatulaand the cup was spun again for 45 seconds at approximately 3450 RPM. Theresulting emulsion consisted of an aqueous oil-in-water (o/w) bimodalemulsion of the silicone and acrylic polymer having a total silicone andacrylic content of approximately 71 and 13 percent, respectively. On adry basis, this emulsions contained approximately 84 percent PDMS and 16percent acrylic polymer. Particle size of the emulsion was determinedusing a Malvern Mastersizer® and the results were:

Dv50=10.917 μm, Dv90=26.833 μm, Mode 1=0.0751 μm, Mode 2=10.226 μm.

Example 10 Bimodal Emulsion at 88% Si—Emulsification of 600K PDMS With1785 Emulsion

42.87 g of 600,000 centistoke (cSt.) Dow Corning® 200 Fluid, apoly(dimethylsiloxane) fluid, was weighed into a Max 40 cup followed by8.55 g of Xiameter® MEM 1785 Emulsion which is a 60% aqueous emulsion ofhigh molecular weight OH functional poly(dimethylsiloxane). The cup wasclosed and placed inside a DAC-150 SpeedMixer® and the cup was spun atmaximum speed (3450 RPM) for 30 seconds. The cup was opened and thewalls of the cup were scraped with a spatula and the cup was spun againat maximum speed for 30 seconds. 8.57 g of 1785 Emulsion was weighedinto the cup and the cup was spun for 30 seconds at approximately 2500RPM. The resulting emulsion consisted of an aqueous oil-in-water (o/w)emulsion of silicone polymer having a total silicone content ofapproximately 88.6 percent. The resulting emulsion was a free flowingopaque material in the dental cup after mixing.

Comparative Example 1 Monomodal Emulsion at 88% Silicone

53.22 g of 100,000 centistoke (cSt.) Dow Corning® 200 Fluid, apoly(dimethylsiloxane) fluid, was weighed into a Max 40 cup followed by1.2 g of Brij 30, 1.45 g Brij 35 L, and 4.26 g of water (addedincrementally). The cup was closed and placed inside a DAC-150SpeedMixer® and the cup was spun at maximum speed (3450 RPM) for 30seconds. The cup was opened and the walls of the cup were scraped with aspatula and the cup was spun again at maximum speed for 30 seconds. Theresulting emulsion consisted of an aqueous oil-in-water (o/w) emulsionof silicone polymer having a total silicone content of approximately 88percent. The resulting emulsion was gel-like and formed a solid cone ofmaterial in the dental cup after mixing.

The invention claimed is:
 1. A process for making a bi-modal emulsioncomprising: I) forming a mixture comprising A) 100 parts by weight of ahydrophobic oil, and B) 1 to 1000 part by weight of a water continuousemulsion having at least one surfactant and II) admixing additionalquantities of the water continuous emulsion and/or water to the mixturefrom step I) to form a bi-modal emulsion, wherein the water continuousemulsion is a silicone emulsion and the bi-modal emulsion contains lessthan 1 weight cyclosiloxanes.
 2. The process of claim 1 wherein themixture of step I) consists essentially of components A) and B).
 3. Theprocess of claim 1 wherein the additional quantities of the watercontinuous emulsion and/or water added in step II to the mixture fromstep I is done in incremental portions, whereby each incremental portioncomprises less than 50 weight % of the mixture from step I and eachincremental portion of water continuous emulsion is added successivelyto the previous after the dispersion of the previous incremental portionof water continuous emulsion and/or water, wherein sufficientincremental portions of water continuous emulsion and/or water are addedto form the bi-modal emulsion.
 4. The process of claim 1 wherein thehydrophobic oil is a silicone.
 5. The process of claim 1 wherein thehydrophobic oil is an organic oil.
 6. The process of claim 1 where thequantity of the water continuous emulsion and/or water added to themixture provides a bi-modal emulsion containing at least 75% by weightof components A) and B).
 7. The process of claim 1 where the bi-modalemulsion has a viscosity less than 100,000 cP.
 8. The process of claim 1where the surfactant concentration in the bi-modal emulsion is less than1 weight %.
 9. The bi-modal emulsion produced by claim
 1. 10. Theprocess of claim 4 where the bi-modal emulsion has a viscosity less than100,000 cP.
 11. The process of claim 3 wherein the hydrophobic oil is asilicone.
 12. A process for making a bi-modal emulsion comprising: I)forming a mixture comprising A) 100 parts by weight of a hydrophobicoil, and B) 1 to 1000 part by weight of a water continuous emulsionhaving at least one surfactant and II) admixing additional quantities ofthe water continuous emulsion and/or water to the mixture from step I)to form a bi-modal emulsion, wherein the hydrophobic oil is a siliconeand the bi-modal emulsion contains less than 1 weight % cyclosiloxanes.13. The process of claim 12 wherein the water continuous emulsion is asilicone emulsion.
 14. The process of claim 12 wherein the watercontinuous emulsion is an organic emulsion.
 15. The process of claim 12where the bi-modal emulsion has a viscosity less than 100,000 cP. 16.The process of claim 12 where the quantity of the water continuousemulsion and/or water added to the mixture provides a bi-modal emulsioncontaining at least 75% by weight of components A) and B).